1. 不用说,参加面试时应该穿上正式的衣服。Needless to say,you should wear formal clothes to go for a interview.
2. 不用说,空着肚子劳动是很难的。Needless to say,it's hard to do some work without any food.
3. 不用说,启程旅行之前应该要先将车子加满油Needless to say,the car should be full of oil before set out on a journey.